How do brain circuits control the temporal structure of behavior? Songbirds provide a marvelous animal model to address this question. By recording from neural circuits, and manipulating them with temperature to observe the effect on song, we have been able to localize cortical premotor circuits that control song timing. One such circuit generates ‘random’ patterns of activity that drive the ‘babbling’ vocalizations of young birds. Another circuit generates a highly stereotyped sequence of bursts that controls the precisely-timed vocal gestures of adult song. Intracellular neuronal recordings during singing support the hypothesis that this ‘clock’ sequence results from a wave of activity propagating through a synaptically-connected chain of neurons. Recently, we have found that this extended neural sequences underlying adult song emerges from the successive differentiation of a simple rhythmic juvenile motor program. Altogether, cortical circuits appear to generate a diversity of dynamics capable of supporting a wide range of behaviors.